SurveyUSA has a new Virginia poll showing Republican gubernatorial nominee Bob McDonnell with a 15-point lead over Creigh Deeds, his Democratic opponent, among likely voters. ...

SurveyUSA has a new Virginia poll showing Republican gubernatorial nominee Bob McDonnell with a 15-point lead over Creigh Deeds, his Democratic opponent, among likely voters. The rest of the Republican ticket also is in a strong position. Do Republicans really have such a big advantage in Virginia?

Taegan Goddard noted that poll respondents said they voted for John McCain over Barack Obama 52%-43%. Obama won Virginia 53%-46%. In other words, this sample is a net of 16 percentage points more toward McCain voters and away from Obama voters than the actual 2008 Virginia presidential electorate. If SurveyUSA had sampled an electorate that matched the 2008 presidential electorate, it's reasonable to assume that Deeds and McDonnell would be in a dead heat.

That, however, doesn't necessarily mean SurveyUSA did anything wrong.

We've now seen two post-primary polls in Virginia that showed McDonnell with a healthy lead. Public Policy Polling gave McDonnell a six-point edge. In that poll, the electorate also was suspiciously favorable to Republicans. (Rasmussen also recently weighed in, putting the Republican's lead at three points.)

The more I think about this, I believe it's possible that core Democratic voters - liberals, African Americans, Latinos, women - aren't nearly as motivated this year as they were last year. There's also the issue of "federal voters" not voting in non-federal elections. In short, what we could be seeing is that Virginia '08 was a totally different electorate than Virginia '09 will be.

That sounds like a plausible explanation. If even a relatively small percentage of Democratic voters are resting on their laurels or if Republican voters are especially desperate for a victory, pollsters would rightly show Republicans making up an unusually large share of likely voters.

Assuming that explanation is right, the question going forward is whether the excitement of a campaign can reverse the Democratic apathy. Democrats' challenge in Virginia this fall will be as much about motivation as it is about persuasion.